The WWII-era 20 Francs "Pêcheur" (fisherman) note is very common in France, but something not known by many people is that towards the end of the war, partisans supposedly began cutting out the portraits of Hitler on German stamps and glueing them onto part of the 20 franc note's obverse, making it look like the fisherman, instead of pulling in a net, was strangling Hitler with a rope.
I've seen a few of these for sale in person and online, but I've never paid for them because like anything that's valuable because of post-production damage (e.g. countermarks on coins) it's hard to tell whether the product is real or made yesterday. It's known that people are producing these today to sell at a premium to collectors, given how cheap and available Nazi-era German stamps featuring Hitler's head, and the 20 Franc notes are, it's very plausible indeed.
Versions with the head of Maréchal Philippe Pétain, chief of the Vichy State, are also available, since his head was also on common stamps.